textproduct: Rapid City

KEY MESSAGES

- Very hot temperatures will continue through much of this week, with record high temps possible and dangerous heat.

- Near-critical to critical fire weather conditions will continue this week.

UPDATE

Issued at 1026 PM MDT Sun Jul 12 2026

04z surface analysis had high over IA with a trough from eastern MT into eastern UT. Decent gradient inbetween supporting gusty south/southeasterly winds at times, especially over northeastern WY/northern slopes of the Black Hills. 00z KUNR sounding tells the story, capped and toasty. Water vapour loop had high over the northern plains with monsoon moisture bubbling up over the western CONUS.

Preponderance of guidance shows strong upper/thermal ridge sustaining itself over the CWA through Tuesday. Western edge of the ridge weakens slightly by mid-week and then more so by the weekend. Monsoon moisture will eventually wrap into the CWA by the end of the week which may bring some convection, especially in/near the higher terrain of the Black Hills. Near-record/record MaxT foreseen given probabilistic guidance and forecast soundings at least through Wednesday. Took another look at 4 days straight of heat indices 100F+/heat index greater than 105F (for Extreme Heat Warning) and the probability is low over far northwest SD with lesser chances further south. So, will continue with Heat Advisory through Thursday.

DISCUSSION

(This Evening Through Sunday) Issued at 228 PM MDT Sun Jul 12 2026

Extreme upper ridge continues to sit across the northern Plains through the central Rockies. At the surface...low pressure across Wyoming is keeping winds at 10kt or less across most of the NE WY plains. As expected, temps are in the triple digits. The hottest temps nearby are across far northern Campbell County through southeastern MT into Butte County, in the 105-110F range. Unofficially, the warmest temperature in the CWA so far is 111F at a RAWS station in northern Campbell County. Not much change to the pattern is expected through the next several days, with highs at or above 100F across the plains each day through at least Thursday. Therefore, have extended the Heat Advisory through then. Contemplated upgrading part of the CWA to a Extreme Heat Warning based on local criteria (100F+ apparent temp for four days or longer) but will keep it simple w/ the Advisory since apparent temps become marginal past Tuesday as drier air moves in from the west, dropping dewpoints 10-15F. This will lower apparent temps across the majority of the CWA to near or below warning thresholds. Regardless, it's splitting hairs since it will still feel hot. Medium range models show some relief coming next weekend or early next week as a cold front finally pushes through.

AVIATION

(For the 18Z TAFS Through 18Z Tuesday) Issued At 1110 AM MDT Mon Jul 13 2026

Expect VFR conditions through the forecast period. Gusty south/southeast winds will persist over the western SD plains today.

FIRE WEATHER

Issued At 228 PM MDT Sun Jul 12 2026

Strong high pressure over the region for much of the week will bring very hot temperatures, along with dry air and breezy winds. Very low humidity and breezy winds will continue through this afternoon and early evening, bringing critical fire weather conditions from the northeastern Wyoming to the far western South Dakota plains. On Monday and Tuesday across much of the western South Dakota plains, winds will again become breezy with gusts up to 35 mph and combine with the very low humidity of 15% or less to support critical fire weather conditions. In addition, poor humidity recoveries are expected each night. A Red Flag Warning has been extended until Tuesday evening. Will continue to monitor the potential for critical fire weather conditions for the second half of the week.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Heat Advisory until 9 PM MDT /10 PM CDT/ Thursday for SDZ001-002- 012>014-025>027-030>032-041>044-046-047-049-072>078. Red Flag Warning until 9 PM MDT Tuesday for SDZ322>332. WY...Heat Advisory until 9 PM MDT Thursday for WYZ054>056-058>060.